SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '333389700665db81241d678a096ebd179702c378258506a82d026a3656806f02' 
  AND token = 'DDtag0I1PmnHVfVOV23KE9II8EBbpWD+NJs/tnbHWJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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