SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c308e7763bf648f30681038b76a44c6bab7dc7a25e29e7db41178d67913f6c2f' 
  AND token = 'LU8DG5ritidyLj/ZgFtJSaK+U/m5hNMyf7Z82AyUY4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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