SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8efd6e83ecc56bb00fb847779e0fe992a268acd93e0cc39e0b9fee724ccd174' 
  AND token = 'Rx59jISQkjDAGSDcbZa+DRZieYcWQwk4m6V7pZylwro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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