SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9629283d3d6ecc7fbe5d412054a1a2292a34e9377636875a69a8d048f9926e1e' 
  AND token = 'V6NpQ+1OUUQ8z4bJ/hbePVSpOIpWGUZf2iTgNRIhoqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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