SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9644c27d215123eb39beeb463662b27d51406059cdcc14017e698a4072ccf9f1' 
  AND token = 'C+VWvrPo8zh2JalHsPqV+Se6kU+8/mN8UllvTCPPVxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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