SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '678ec06193da2cdc9d51d6a12838a1a71455b14a189f4bcf14426c18f8432168' 
  AND token = 'JrOvU8xE26goxSqWBI7aeCELA0aCfiIeIeVKTXfsIEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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