SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c4e0d023e56a9d0e565027efe6993fe8798552ebcb6ab8322465462d4dba0e60' 
  AND token = '4ca8sMeREHUDpt9zsueyZVQagT0QgR/QLN4JQMBMC3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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