SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a38330e06b393c02942df9918f0b21548f578bec1c7253ca8c0a1b58be01e83c' 
  AND token = 'PQqANUq8x9FIJdwqK4lgyOZRhjLhHj+DTx6G0AEnZqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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