SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '95f4af1075ef3791edf0580a5d24471f6738f8f42e17bc66ea16822a90c27968' 
  AND token = 'sVLg/FpkKuGjl5sJGdu1ICadWMNIVZyp2sPs3tOQWk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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