SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef77fe8875f9693c710789eacfcdd4b2cef4d70189962f290ca7fc2a9a117f81' 
  AND token = 'ErEuQxacoMZpMuLl1iYHPFIcP8YlBDunz8zAJ4LFhEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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