SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3713b60651e427a039b2295d259402fbdbed4a5979c11607a02b6012c4809fc2' 
  AND token = 'wbLoPe4MPrZBvZqr4q5+Mpg3920Gek7fCbxvdX5aAHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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