SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c50a54011713a2a533cbfd6775b17756a26483a0b82c25aabd331d05c9e0ed5' 
  AND token = 'C0FK7prb2MpiS6UCljhhJHFoRdmE0cEOlyCwPtEeZbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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