SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b7ec646bf1c68ff9138bdcb020e13b35b2c1a6fd53005ce1737196e908eae92' 
  AND token = 'M4LmaRYeYL+HV4yCYPKMsZn7YteNiFprbpJGZzct1wQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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