SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c5f0fdd5330980167e1e8f9a93a9136f4b1821727802981fd07ad578e166037' 
  AND token = '5mjIrA5LZnr2aEp8cGI/NYO7Frm7/RAxtXoOfTL3k78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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