SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c73256fcdd4a814a276a1382e16aef0242bb006d72b47362322c1c3791e128e4' 
  AND token = 'qaiPiOuw/4pwc1GbBEsCypA3O4ypPXYah8Juzi8tMc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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