SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74abfc89209bd6a74f4bcd5f31783466975221c7d8e829636813ccfeec3e9e4b' 
  AND token = 'y0wo+BaWBfK39RPxmOVMMEMyzrUtkEcVM4It02y5uXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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