SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f9c606d5bed082db73db5a2c26a16b349579858a4b7f3197607759a63afd63' 
  AND token = 'zftMaRgbFRBlUKBByu/cTXvsU1cVtu2kQvYYnUQHVJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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