SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e51f8f27de10f30c6f645c954bdd42da19dd084b531347d6389ac3f7a7651375' 
  AND token = 'HJ+VWPR+qfFxBsE4euqV8wWJeJOyJC9oF1z8aGYprks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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