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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '984f4f3b1fe4efacd2d998edfd15b414c83e6d698a306c0aa4c2c65ce32d9409' 
  AND token = 'Lj3kVLoX1Q5yWMfvfnkO2a6Mi/QIphnHjmEDHTgIP5w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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