SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14c7f0fb1a940ac1d5bfad784bd86fa267e1745bfcfe73f98973ee4c2ed84bba' 
  AND token = '/tPV/3kHmPCElkQd3sqhXs1SPORfic4IFSCuKnu+jWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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