SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7db2a8a674408d008c9ca88328102a27fe79707a75e2098e7591ec48cdafde19' 
  AND token = 'G4GlTnLPVjLWgbPePdxTPjfOHYqjCIdlf9v+xnp0kJI=' 
  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"
    }
  }
}