SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3f2c081a7e63bd7acd697f49a502e63e823f48efc558719f696582a6fcbf539' 
  AND token = 'e5nY7H0szBbps129lamtznUWDtTiORtuibWiZhZhXQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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