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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f038c9ca384e27ee324ff0f8b1804d0db32b08d8866f8a4e3e7c0e26200d62f3' 
  AND token = '/iVPV+LLRiOWF+v1T88nBnWEL2Wj0kcyh8Jh/NesV5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}