SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e752cf8c6bf234564ef11d69be30c806105f7c893c065a19d854eb2213f9ff50' 
  AND token = '4ZNnLK294W46kJwkNK6nf8j8CbqP+Q8mHzMKrHfqOIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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