SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f8db70cccb5828a5cb755e640c3e4b385eca59be51b4239f3065d7d92dfd861' 
  AND token = 'u+BWsTPewWPHpL3FidWLCZrWo0Clqs1eF4Cp1U8LckQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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