SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98e68df1b57d84851586c6ad43beeb812f3028123ed1ec82c23934865444857f' 
  AND token = '6AvzZUQ/xHo2pbUE5vMV5FVuMHio9HArEnsOBefrlhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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