SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a4a21d8181aeb48604176aa19a0a7913b1498c23b758bb839a6804568a7578bd' 
  AND token = 'boBXaNO4nCeVEcYjOnTxt6Vx29rmyFUQ8o3JJkOUnmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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