SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53b0ce254b2c2115b7289c82126bd317f41631d40116a241d63e1c0eb26fc130' 
  AND token = 'NkbLulwggqciaY/k+kIxv0gcKYonf6AT+bUb1LMvvxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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