SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53fcd83ab0bab15b5ed0490db6df11a68adf76d81d9e1dddebdd27311980b0ba' 
  AND token = '7MsvTkiVUunucetjBSmKdM3fYnLRwsRBwV5tevJtoYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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