SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e8089cf582980d2726864d51621b0bdaf34bb375d27c455688b63f8ef2dcd57' 
  AND token = 'Agt3RC6tTRpTl95ga9uWqwJd2JWQElW+skME4+qbeiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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