SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2f9b08042e0ae946834926516bfe289df9feef40437981eac8ed1f1c12378c5' 
  AND token = 'MDDTqDCWtlwfV/vqs73mjKP/wOTECZCU7UJebdh80vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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