SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dbbab6cd0a70684f3e86d5de9a2dfdf87aaaac19bbf2375b13e982759aba831' 
  AND token = '6HmvGgjljcgKn4HOBua7TRC9qKTtAMivgz2Cnuhlo5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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