SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd14d56457142556c937e52276df1333601dae0b149a9bf537922048357a512b4' 
  AND token = 'L4t/GhYJJCSz7G7Rb4hK6cKZf+QvYh7h/+4OjoiHzyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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