SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'ad4917edc99898363ff4c6f7c6ece089f8cc030c7680c85f8373c8ac74523d68' 
  AND token = 'k5Gxh9coP2IQy/vz5K2psvxCroW2n8bw+mll3UGKYB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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