SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '400affafa6cfd3f96e337b50f3dadff42988f6820c84a4d0f4bf81377402f780' 
  AND token = '7xnawPQTSCE4dmbyLNcECanjtjQxKtaaUA/7ijEJjkM=' 
  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"
    }
  }
}