SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'add6a18acc89076c69cde1a61f943d90ca7c860a3b994a90374bf05595a5362e' 
  AND token = 'hVy580U7w41nSUb9GqBQWHyyN3jxLAykIhRJWtgoJ0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}