SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '60b4a6d868ece22a629b528c60ebc32b3d7cf7874f7f463c6e2471b4734904b7' 
  AND token = 'StMmQQArOAh0gmNXK80+4ed/RATWcgFSIKkoxyriPws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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