SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92d35c9484882cb6216124012dfb1bb707546c6fddcce258023abf3638a5b108' 
  AND token = '7TSoXxHXxs6SG6d4vafD4mAEoqXrLNaMCpB3fpbB3rM=' 
  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"
    }
  }
}