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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28ce4b5ae996a6d8d1b6c33097267a5d5641166b568cb870b8badac61c5b3e3a' 
  AND token = 'Sc3DrpWO5s3ASaHt+TLcROk2rSUPYk+rdMUzPVOqdqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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