SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c1c6b2e8bf76e8ecf216dae8c1d56b51bbee58aeb7a2b6d859a4edcbaff0b844' 
  AND token = 'KQCehUk53uydIxK21KLnM5OV87CQhgqAHCDBWsgyxNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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