SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18fee9231d78f5445a0a0317264de31b0e56128041869bf3e1c568262ce9d17d' 
  AND token = 'gGMrku3SFK9DmSGIkswnWtzaHUXQlAIJpDfcaqoL+58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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