SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6458592fd97377032626f518a5303e2f20f3af0bb55e971c995d01c9d58dc58' 
  AND token = 'trZjCq2xzdV75eLuQOEOqaVmzhODWui8Ug2Hb/OjrSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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