SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73763d87025c9d2161e14741c8cd50349566b175475181ea37c444702537feba' 
  AND token = 'ya8XkuVzqcl+f4RQJZ/DG5EkDipXQWTx8VDYn3voIhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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