SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c326de4c5d7f8275eb66206c63aebed0d13eaabdfaa37a344b62417c4a658820' 
  AND token = '4j5ROvcpFg3Arih3+hFjYC9njlwRHvTz7XzWxqh4IUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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