SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'd88ef16aee49d3c31faf12764d0c55340a83f2c52dd9eecd01cc0789cb734914' 
  AND token = '4SxmGqNLVk1QuwERy9n7Ry3kxKTJ5JmWfYOG9zZwvjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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