SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '856983d774c4c3655fc6866d58907e3111fb7124a505024942928ecfd509ced1' 
  AND token = 'Kw0Cne/uwyRFLSdGWLImDvwkTMOUkYS34S7QbMmgBPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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