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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2710eae49fc9c9cc837545297a8d7035aa6641342098852c7bdf70e8f3e2d4b5' 
  AND token = '3mrf3Bam+4PQvbgkAP9t2niqHnPGn69DECnsN2Hg2kI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}