SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbedb7897cceb53e856a2e703cb2aa8621fb523cd049002052a1bcead7b23910' 
  AND token = 'fUubsTq7HEDml2dF/cTLGrCEv6PN20AbN20lDQwY4cI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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