SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '84b918872e682f39c4d1b4c970cb61ca275505f7cac9c493b7b7573aee0c6c0b' 
  AND token = 'oS8bDkQCQhYjKOU35i0gYEgZ781+wBNhFLuDfTtQQ3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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