SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6b0c2d2920236795dd7218cc9c62f22d50ed4b7c7cca3dac1549aaa8b8304412' 
  AND token = 'Q2fusXTzB9Qw4zYEOw2KGFGhlC+FIizfGLHgHFvJtQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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