SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0dfb5b6fcda93226fc586b28620ebcdc2f21953637739e6d0fd342be2ae1f8' 
  AND token = 'AOEQNgZ8+aGWjeVRzq3Ts9+a9/xi/LOzI/KhzQzl2Vk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}