SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2c329dd966eb4bc18249fccd458cbd9113942ec4783aa81a32b4a4403819851' 
  AND token = 'EwzlMOkXjoRAgLf7iUWxfJM2TXXVTxMtrhxfzACyOm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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