SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e53857b29dff1bbec5d84f3c4036962107b5da084c2ffc13683cc01f0da53fd8' 
  AND token = 'M1aHzKTH9FgHhdggzed817yklPx4JKgeFgkyFRlIw40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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