SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '620f851a381c2ef3bdf5aaedc91e54ddab786741b238c2f1e1281442f407ac88' 
  AND token = 'B8XHP6cYciZcAZIgjCqV38gc8J7aQqvDZZbwmPh1Ggg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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