SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4012a661217a74543268099fbb6ecb3420ecf3d81ccc17b3ceeb4ff06474206c' 
  AND token = 'DVZuI7xfD2knoUlA6JqdYkXUsTHE+hk7lPVjvGGwOJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00064

JSON explain

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