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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d7ebe798094e0f2dd5347e28abe4c7e8b66a061687bd81a7052c31d2cf84afd' 
  AND token = '6mcG1iJw4ECcSCD7WOXm52gDXcKDtcDbe/L4XT0Nx8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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