SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9108b11a2faa2e41640fdbef274013a7a9b4a7053fe1746416d107aa4fb5487e' 
  AND token = 'CLu+ajXYxsdDUA5m8raEUv4Ympp8Qmtjex+gVe6Tkh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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